Document clientside-pagination directive behavior

[Copilot]

Adds documentation for the clientside-pagination directive in the directives guide, covering expected behavior and usage patterns.

• Directive coverage
  • Adds a new “Client-Side Pagination” section describing how the directive hides pagination parameters, auto-iterates pages, and when to use it
  • Includes standard usage and regex selection examples

Example:

# Enable client-side pagination for all Get-*List cmdlets
directive:
  - where:
      verb: Get
      subject: (.*)List$
    set:
      clientside-pagination: true

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add doc for the clientside-pagination directive</issue_title>
<issue_description>Add a section in https://github.com/Azure/autorest.powershell/blob/main/docs/directives.md to describe the clientside-pagination directive.

Implementation details are in this pull request: #828</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add doc for the clientside-pagination directive #1109

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